People on this site probably interact with computers much more than the average person, and many type stuff into their machines for the majority of their days. I don't see why it wouldn't make sense to get yourself something decent that feels good to interact with there.
Tiny annoyances multiplied by a hundred times a day, 365 days a year add up. And even if it is only that slightly mushy Ctrl key or that spacebar where the right stabilizer is weird because the thing fell off the desk once.
For me a mechanical keyboard must be sturdy, heavy, with no flex of any kind. Preferable with black linear/silent switches, something that you can punch in hard or type completely silent if needed. Not a piece of plastic that moves around on the desk.
Maybe the fact that I am playing musical instruments (and work in audio) plays a role here. Tactile feedback is very important to me. I don't need a click, just very predictable and reliable responses that don't distract me when I am in the flow. I need a keyboard that can be silent if I need it to be silent.
That alone (for me) justifies spending more money than usual people would spend on a keyboard. It is not hobby to me, it is a tool. But a tool I enjoy using and that works for my use case. Sure I could use any other keyboard. But I don't have to, so why would I?
A year ago I lost a lot of free time and realized how much crap I was unnecessarily putting up with. I've started trying to upgrade the tools that give me the most friction, and many times it's been surprisingly inexpensive for the benefit gained. I bought one decent keyboard and mouse that can switch between multiple devices, replaced my terrible second monitor with one that has better viewing angles, and took in my kitchen knives to have them sharpened. There are (obviously) still many annoyances during the course of a day, but there's just a little less overhead involved in getting work done.
What's the advantage of backlighting? I don't need to look at my keyboard to type.
And some people do not 100% touch type, or don't touch type in the strict way everyone expects all touch typists to do so.
It just gets weird when people start into these audiophile-like arguments for the superiority of their choice. I've owned a number of mechanical and membrane keyboards since my first computer in 1983, and there's no real benefit to either except for aesthetics and how it feels to you personally.